Event-related potentials (ERPs) recorded from the human scalp vary systematically with the information-processing requirements of cognitive tasks. One such task involves the active categorization of stimuli into predefined categories. ERPs during such tasks are sensitive to the effects of stimulus significance (the eliciting stimulus must be task-relevant), stimulus sequence (ERPs are larger for stimuli preceded by a stimulus from another category), and stimulus probability (ERPs are larger for stimuli with low presentation probability). Because of these effects, scalp ERPs have been studied extensively as a means of investigating the neural substrates of human cognitive processes. However, such efforts have been hampered by the lack of information regarding the neural sources of human task-related ERPs. Recent human intracranial recordings have demonstrated ERPs from medial temporal lobe structures which overlap in time with task-related ERPs on the scalp and have similar relationships to task variables. We propose here to continue development of an animal model for such task-related ERPs based on two-tone discriminative conditioning of the rabbit nictitatng membrane response. Preliminary experiments have demonstrated that task-related ERPs can be reliably recorded from multiple brain sites in this paradigm. Three experiments are proposed: Experiments 1 and 2 will investigate the behavioral properties of the task-related ERPs demonstrated in the preliminary experiments, and Experiment 3 will begin to investigate their neural generators. Eventually we hope to identify the anatomical and physiological substrates of these task-related ERPs. Such information will contribute to an understanding of the neural bases of human cognitive processes and to the use of ERP methods in assessing cognitive disorders.